linux-cve-announce - CVE-2025-40236: virtio-net: zero unused hash fields

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Message-ID: <2025120402-CVE-2025-40236-617c@gregkh>
Date: Thu,  4 Dec 2025 16:32:11 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-40236: virtio-net: zero unused hash fields

From: Greg Kroah-Hartman <gregkh@...nel.org>

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

virtio-net: zero unused hash fields

When GSO tunnel is negotiated virtio_net_hdr_tnl_from_skb() tries to
initialize the tunnel metadata but forget to zero unused rxhash
fields. This may leak information to another side. Fixing this by
zeroing the unused hash fields.

The Linux kernel CVE team has assigned CVE-2025-40236 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 6.17 with commit a2fb4bc4e2a6a031683910d85b278c1d25ae5420 and fixed in 6.17.6 with commit b625d231c66a6041e98817ffc944bf6e4c45b2e3
	Issue introduced in 6.17 with commit a2fb4bc4e2a6a031683910d85b278c1d25ae5420 and fixed in 6.18 with commit b2284768c6b32aa224ca7d0ef0741beb434f03aa

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2025-40236
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	include/linux/virtio_net.h


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/b625d231c66a6041e98817ffc944bf6e4c45b2e3
	https://git.kernel.org/stable/c/b2284768c6b32aa224ca7d0ef0741beb434f03aa